1. Field of the Invention
The present invention relates to an ink composition, an image forming method, and a printed article using the same.
2. Description of the Related Art
As image recording methods for forming an image on a recording medium such as paper based on image data signals, there are an electrophotographic method, sublimation- and fusion-type thermal transfer methods, an ink jet method, and the like. The electrophotographic method requires a process for forming an electrostatic latent image on a photosensitive drum by charging or exposure, so the system becomes complicated. As a result, the method has a problem of the increase in production cost and the like. In addition, though the device for the thermal transfer method is inexpensive, the method uses ink ribbons. Therefore, the method has problems that the running cost is high, waste materials are produced, and the like.
On the other hand, in the ink jet method, an inexpensive device is used, and an ink is discharged only to a necessary image portion to directly form an image on a recording medium. Accordingly, the method is advantageous in that the ink can be used efficiently and the running cost is low. Moreover, the method generates little noise and is excellent as an image recording method.
Among ink compositions used in image recording performed by the ink jet method, an aqueous ink using latex can be suitably used not only in image printing, but also in pre-treatment for imparting printing suitability to a recording medium, post-treatment for protecting and decorating the printed image, and the like. Moreover, containing water as a main component, the aqueous ink is excellent in safety and is applicable to high-density ink jet recording due to its low viscosity. In this way, the aqueous ink using latex is a technique having various excellent characteristics and potential.
As an example of basic constituent materials of the aqueous ink containing latex, there is a disclosure regarding an ink composition that contains water, acrylic polymer latex having a particle size of about 200 nm, a water-soluble organic solvent, a pigment dispersion, and a surfactant and exhibits excellent ink resistance after drying or discharge properties (for example, see JP2011-507991A).